The purpose of time switch clocks is connecting and disconnecting electrically controllable apparatus, such as space heating systems, at given pre-set times. Additional functions can also be performed manually or by means of the time switch clock, such as the connecting and disconnecting of the device by manual operation, for example. Mechanical time switch clocks have recently been increasingly replaced by electronic time switch clocks. The electronic time switch clocks provide additional capabilities, such as connecting and disconnecting at different times on individual days of the week. It is thus possible to store a time program for connecting and disconnecting on each individual day of the week or for a group of days and to access the program on individual weekdays.
One such microcomputer-controlled program-setting device used as a heating regulator is known, for instance, from the journal "Elektronikpraxis" No. 10, October 1981, pages 154 and 155. The control device of the heating regulators is so constructed that it has an electronic time switch clock which can be set in conventional manner, a microcomputer and a function switch. The individual stages of the function switch make it possible to set the time, to store a program for connecting and disconnecting, to associate the connecting and disconnecting with individual days of the week, and to effect a permanent connection or disconnection of the attached device.
This known program setting device has the disadvantage that the programming requires specialized knowledge. When there is only occasional use of the control device, such as for re-programming due to holidays, the previously acquired knowledge of operation is frequently forgotten between the uses so that the operating instructions must in each case be consulted again. This is inconvenient, on the one hand, and on the other hand, there is the possibility that the operating instructions have been misplaced.
There is a need for a program-setting device which guides the operator by interrelating the operating and indicating elements in an easily understandable manner. The device should position them in such a logical way that even a technically inexperienced operator can effect the programming without operating instructions. For this purpose it is also necessary that erroneous manipulations do not invalidate the already properly programmed part but, instead, the error is tolerated or indicated as such and the proper procedure is shown. The operating of the keys should furthermore be adapted to each individual sequence of thought, i.e. there should not be required a specific sequence in the setting of the various parameters which can only be ascertained from the operating instructions.